Burner unit

ABSTRACT

A BURNER UNIT COMPRISING MEANS DEFINING A COMBUSTION ZONE, MEANS FOR SUPPLING AIR UNDER PRESSURE TO THE COMBUSTION ZONE, THE AIR SUPPLY MEANS HAVING MEANS OPERATIVE TO REGULATE THE AIR INTAKE THEREOF, MEANS FOR SUPPLYING FUEL UNDER PRESSURE TO THE COMBUSTION ZONE TO PROVIDE A FUEL-AIR MIXTURE, THE FUEL SUPPLY OF FUEL TO THE MEANS OPERATIVE TO REGULATE THE SUPPLY OF FUEL TO THE COMBUSTION ZONE, ACTUATING MEANS OPERATIVELY INTERCONNECTING THE AIR INTAKE REGULATING MEANS AND THE FUEL SUPPLY REGULATING MEANS MOVABLE BETWEEN PREDETERMINED LIMITS TO ACTUATE SAID REGULATING MEANS, AND MEANS DISPOSED IN THE COMBUSTION ZONE FOR IGNITING THE FUEL-AIR MIXTURE.

a 71 w. F. JACKSON ETAL. I v 3,556,709

BURNER UNIT Filed Dec. 17, 1968 v 2 Sheets-Sheet 1 INVENTORS WALTER F. J'AcKsoN JAMes F.W\sE

ATTORNEY3 Jan. 19., 1971 w. F. JACKSON ETAL. 3,556,700

I BURNER UNIT Filed Dec. 17, 1968 .2 Sheets-Sheet z '41 1 I "rig-2 INVENTORS WALTEQ F. J'AcKsou JAMES F. Wse

ATTORNEY 8 United States Patent 3,556,700 BURNER UNIT Walter F. Jackson and James F. Wise, Clinton, N.C.-, assignors to Van Industries, Incorporated, Clinton, N.C., a corporation of West Virginia Filed Dec. 17, 1968, Ser. No. 784,430 Int. Cl. F23n 1/02 US. Cl. 431-182 Claims ABSTRACT OF THE DISCLOSURE A burner unit comprising means defining a combustion zone, means for suppling air under pressure to the combustion zone, the air supply means having means operative to regulate the air intake thereof, means for supplying fuel under pressure to the combustion zone to provide a fuel-air mixture, the fuel supply means having means operative to regulate the supply of fuel to ,the combustion-zone, actuating means operatively interconnecting the air intake regulating means and the feul supply regulating means movable between predetermined limits to actuate said regulating means, and means'disposed in the combustion zone for igniting the fuel-air mixture.

This invention relates to a burner unit and more particularly to a burner unit which may be readily adjusted to provide different firing rates.

In the production of tobacco, when the tobacco leaves are primed in the field, they most often are secured to tobacco sticks to facilitate subsequent handling. Generally, the sticks of tobacco are transported to curing barns for curing prior to marketing. Curing barns normally consist of relatively large enclosures having racks for mounting the tobacco sticks. In addition, there usually is provided a burner unit and a heat distribution system for heating the barn to cure the tobacco.

The tobacco curing process generally consists of two stages. In the first stage, the tobacco leaves are subjected to a relatively low temperature in the range of 90 to 100 F. for a period of about 30 to 60 hours, during which physiological transformations occur in the leaves. This stage normally is referred to as the yellowing stage. After the leaves have turned yellow, they are then subjected to a higher temperature in the range of 130 to 135 F. for a period of 20 to 30 hours, during which the physiological transformation of the leaves is halted and the leaves are dehydrated. I g

In the prior art, various types of burner units have been used in the curing of tobacco leaves. It has been found, however, that most of such burner units are not the accompanying drawings, wherein:

"ice

A further object of the present invention is to provide a burner unit operable to provide different firing rates with maximum combustion efficiency.

Another object of the present invention is to provide a novel burner unit which is simple in construction, com paratively inexpensive to manufacture and simple to operate.

Other objects and advantages of the present invention will become more apparent to those persons having reasonable skill in the art to which the inventionpertains, from the following description taken in conjunction with FIG. 1 is a perspective view of an embodiment of the invention; and

FIG. 2 is an enlarged cross-sectional view taken along line 22 in FIG. 1.

Briefly described, the present invention relates to a burner unit having at least two'different firing rates com prising blower means, conduit means communicating with the blower means for receiving air under pressure therefrom, fuel pump means, prime mover means for driving the blower means and the fuel pump means, first and second nozzles disposed in the conduit means, and ignition means disposed adjacent the nozzle means. Also included is a first fuel supply line intercommunicating the fuel pump and the first nozzle means, and a second fuel supply line intercommunicating the fuel pump and the second nozzle means. The second fuel supply line is provided with valve means normally disposed in a closed position, and the blower means is provided with at least one air intake port and shutter means registerable with the air intake port, which is movable to at least first and second operating positions to vary the effective opening of the air intake port. Also provided are actuating means operatively interconnecting the valve and the shutter means which is movable to a first position to close the valve and i restrict the effective opening of the air intake port, and

readily adaptable to provide different firingrates suflicient to enable the burner units to provide the appropriate heat necessary for the physiological transformation and dehydration stages in the curing of tobacco.

Accordingly, it is the principal object of the present invention to provide a novel burner unit. I

Another object of the present invention is to provide a novel burner unit particularly adapted for curing tobacco.

A further object of the present invention is to provide a novel burner unit adapted to provide at least two different firing rates.

A still further object of the present invention is to provide a novel burner unit operable to provide different firing rates and correspondingly to produce' different heat outputs sufficient for effecting sequential physiological transformation and dehydration of tobacco leaves in curwhich also is movable to a second position to open the valve and increase the effective opening of the air intake port.

Referring to the drawings, there is illustrated an embodiment of the invention. The embodiment comprises a burner unit including a blower 10, a fuel pump 11 mounted adjacent the blower, a motor 12 having an output shaft 13 for driving the blower 10 and th'e'wfuelpump 11, an elongated conduit 14 mounted on the blower 10 and communicable therewith to receive a supply of air under pressure therefrom, and an ignition system 15. As best illustrated in FIG. 2, the blower 10includes an air intake section 16 having an annular wall 17 provided with a plurality of circumferentially spaced air intake ports 18. Air received through the air intake ports 18 flows axially into the main body of the blower and is ejected under pressure into conduit 14 by means of impeller 19 of the blower. I

Slidably mounted on the annular wall 17 is an annular shutter 20 having a plurality of circumferentially spaced openings 21 which are registerable with the air intake ports 18 in the annular wall 17. It will be appreciated that upon rotatable adjustment of the annular shutter 20, the effective openings of air inlet ports 18 can be varied to correspondingly vary the air intake of the blower. Cor respondingly, the adjustment of the annular shutter 20 will vary the supply of air under pressure to the conduit 14. Connected to the inlet side of the fuel pump 11 is a fuel supply line 22 provided with a fuel filter 23. The outlet side of the fuel pump 11 is connected by meansof a fuel line 24 to the inlet side of a pressure delay control valve 25 which is adapted to open when the pressure in the fuel supply line 24 exceeds a predetermined pressure in the order of to p.s.i. under normal operating conditions. A T-fitting 26 is connected to the outlet side of the pressure delay control valve 25. One outlet end of the T-fitting 26 is connected by means of a fuel supply line 27 to a fuel supply conduit 28 disposed within the conduit 14. The fuel supply conduit 28 is secured at the rear end thereof to the cylindrical wall of conduit 14, and extends forwardly substantially the entire length of the conduit 14 to a combustion zone 29 adjacent the front open end of the conduit. Disposed in the combustion zone 29 and mounted on the front end of the fuel supply conduit 28 is a nozzle 30. It thus will be seen that fuel supply line 24, pressure delay control valve 25, T-fitting 26, fuel supply line 27, and fuel supply conduit 28 provide a first fuel supply circuit, supplying fuel under pressure to the nozzle 30 which is adapted to disperse the fuel into the combustion zone 29.

The other outlet end of T-fitting 26 is connected to the inlet side of a valve 31 by means of a fuel supply line 32. The outlet side of the valve 31 is connected to a second fuel supply conduit 33 disposed in the conduit 14 by means of a fuel supply line 34. The fuel supply conduit, 33 is connected at its rear end to the cylindrical Wall ofthe conduit 14, and extends forwardly substantially the entire length of the conduit 14 adjacent and parallel to the fuel supply conduit 28. A nozzle 34 is mounted on the forward end of the fuel supply conduit 33 adjacent the nozzle 30 in the combustion zone 29. Similar to the first mentioned fuel supply circuit, the fuel supply line 24, the pressure delay control valve 25, the T-fitting 26, fuel supply line 32, valve 31, fuel supply line 34, and fuel supply conduit 33 provide a second fluid supply circuit, supplying fuel under pressure to the nozzle 34 which disperses the fuel into the combustion zone 29. The forward ends of the fuel supply conduits 28 and 30 are rigidly secured in spaced relation by means of a spacer member 35. Also mounted on the spacer member 35 rearwardly of the nozzles 30 and 34 is a set of impeller blades 36 which operate to impart a swirling motion to the supply of air under pressure traversing the length of the conduit 14.

The burner unit is capable of operating at a first firing rate when the blower and the fuel pump 11 are operating to supply fuel under pressure through the first fuel supply circuit to the nozzle 30 and air under pressure through the conduit 14 to the combustion zone where the supply of fuel dispersed by the nozzle 30 mixes with the supply of air through the conduit 14. The burner unit also is capable of operating at a second higher firing rate when the valve 31 is open to provide additional fuel under pressure to be supplied to the nozzle 34 through the second fuel supply circuit, and the effective openings of the air intake ports 18 are increased to provide an increased supply of air in the conduit 14 which mixes with the additional supply of fuel dispersed by the nozzle 34 in the combustion zone 29. The flow of fuel through the second fuel supply circuit and the increase in the effective openings of the air intake ports 18 is controlled by means of an actuating assembly 37.

- Referring to FIG. 2, the actuating assembly 37 consists of the valve 31, a lever member 38 operatively connected to the valve 31, and a rigid linking member 39 operatively interconnecting the lever member 38 and the annular shutter 16. The valve 31 is mounted on a bracket 40 rigidly secured to the casing of the blower 10 and is provided with an internal passageway 41 intercommunicating fuel lines 32 and 34 and having a valve seat 42. Slidably mounted in the valve is a valve stem 43 having a Valve element 44 secured on the inner end thereof and urged into engagement with the valve seat 42 by means of a spring element 45, thereby blocking the internal passageway 41 and correspondingly the fuel supply circuit for the nozzle 34. The lever member 38 has a bifurcated end. portion defining a pair of spaced ears 46 and 47 as perhaps best illustrated in FIG. 1. The outer end of the valve stem 43 is received between the ears 46 and 47 and is pivotally connected to the bifurcated end portion of the lever 38.by.imeans of a.connecting.pin.48..The bifur:

cated end portion of lever member 38 also is.provided With a cam surface including planar portions 49 and 50 which are selectively engageable with an exterior bearing surface 51 of valve 31. As illustrated in FIG. 2, the radial distance between the axis of the pin 48 and planar cam surface 50 is greater than the radial distance from the axis of pin 48 to the planar cam surface 49, so that when the lever member 38 is in theposition as illustratedin FIG. 2 with the planar cam surface 49 urged into engagement with the valve bearing surface 51 by means ofthe spring element 45, the valve element 44 will engage the valve seat 42 to block the internal passageway 41, and when the lever member 38 is pivoted to-the-position illustrated by phantom lines in FIG/2, the planar cam surface 50 of the lever member will engage the valve bearing surface 51, and the valveelement 44 will be unseated from the valve seat 42 to open the internal passageway 41.

The upper end 52 of linking member 39 is bifurcated to receive the free end of the lever member the'rebetween. The upper end of the linking member is pivotally connected to the free end of the lever member 38 by means of a connecting pin 53. The lower end of the linking member extends through an opening of a lug 54 which is rigidly secured to the annular shutter 16. The relative movement between the lower end of the linking member and the lug 54 is limited by means of a pair of spaced collars 55 and 56 mounted on opposite sides of the ing 54 and secured to the lower end of the linking member with set screws. It thus will be seen that by moving the linking member 39 upwardly to pivot the lever member 38 to the position illustrated in solid lines in FIG. 2, the valve stem 49 will seat the valve element 44 to close the valve 31, and the annular shutter 16 will be rotatably adjusted in a counterclockwise direction to decrease the effective openings of the air intake ports 18. By moving the linking member 39 downwardly to pivot the lever member 38 to the position illustrated by the phantom lines in FIG. 2, the valve stem 49 will unseat the valve element 44 to open the valve 31, and simultaneously the annular shutter 16 will be rotatably adjusted in a clockwise direction to increase the effective opening of the air intake ports 18.

' The ignition system 15 includes an electrical transformer 57 having an electrical supply source and an output connected by means of insulated electrical lead lines 58 and 59 to a pair of electrodes 60 and 61 disposed in they combustion zone 29 adjacent the firing nozzles 30 and 34. It will be appreciated that upon energization of the ignition system,,the,electrodes 60 and 61 will provide a spark to ignite the fuel-air mixture in the combustion zone.

In the operation of the burner unit as described, whenever it is desirable to operate the unit at the first or lower firing rate to provide a lower heat output, the actuating assembly is positioned as illustrated in the solid lines in FIG. 2, so that the valve 31 is closed, thus blocking the second fuel supply circuit and restricting the effective openings of the air intake ports 18. The motor 12 is then started to operate the blower 10 and the fuel pump 11. Initially, air under pressure will be supplied by the blower to the conduit 14. The air under pressure traversing the length of the conduit 14 will engage the set of impeller blades 36, so that the air under pressure entering the combustion zone 29 will have a'swirling motion. After the fuel pump 11 has been operating for a short period of time and the pressure in the fuel line 24 exceeds tolOO pounds, depending on the setting of the pressure delay control valve 25, the valve 25 will open to permit fuel under pressure to flow through T-fitting 26, fuel line 27 and fuel supply conduit 28 to nozzle 30 which disperses the fuel into the combustion zone 29 to mix with the swirling supply of air under pressure. The fuel-air mixture in the combustion zone 29 is ignited by the electrodes 60 and 61 and will continue to burn until the supply of fuel and air is shut off.

It will be appreciated that the cumulative size of the effective openings of air intake ports 18 controls the amount of air supplied by the blower to the combustion zone. Accordingly, the cumulative size of the effective openings of the air intake ports 18 is determined initially and the annular shutter is preset to provide an appropriate supply of air to the combustion zone, thus assuring maximum combustion efficiency for the first firing rate during which fuel is supplied only through the first fuel supply circuit.

Whenever it is desired to operate the burner unit at a higher firing rate, the linking member 39 is moved manually downwardly, so that the actuating assembly assumes the position illustrated by the phantom lines in FIG. 2. As this occurs, the lever member 38 is pivoted about the axis of connecting pin 48 so that the planar cam surface 50 engages the valve bearing surface 52 and the valve stem 43 is retracted, unseating the valve element 44 and permitting the flow of fuel under pressure through the second fuel supply circuit to the firing nozzle 34. Simultaneously with the opening of the valve 31, thus permitting the flow of fuel under pressure in the second fuel supply circuit, the collar 55 on the lower end of the linking member 39 will engage the lug 54 to rotatably adjust the annular shutter 16 in a clockwise direction to increase the cumulative size of the effective openings of the air intake ports 18. The increase in the cumulative size of the effective openings of the air intake ports results in a greater volume of air under pressure being supplied to the combustion zone 29 to combine with the increased supply of fuel, thereby providing a higher firing rate. It will be understood that the various components of the burner unit, including the sizes of the nozzles 30 and 34, the openings 21 in the annular shutter 16, and the components of the actuating assembly must be calibrated to provide efficient fuel-air mixtures for the high and low firing rates of the unit. Once the unit has been calibrated, the high and low fuel-air mixtures providing the high and low firing rates may be established merely by moving the linking member 39 of the actuating assembly upwardly or downwardly.

The present invention particularly is adapted for use in curing tobacco leaves, in that the burner unit can be calibrated to operate at a first firing rate to produce a low heat output sufficient for the physiological transformation or yellowing of the tobacco leaves, and to alternately operate at a second higher firing rate to provide an increased heat output to dehydrate the tobacco leaves following the physiological transformation or yellowing In the use of the aforementioned embodiment of the invention for curing tobacco, it is necessary for the operator to manually adjust the burner unit to provide the higher firing rate when the physiological transformation or yellowing stage of the curing cycle has been completed. Furthermore, with such embodiment, it would be necessary for the operator to shut off the burner unit after the dehydration of the leaves has been completed. It further is within the contemplated scope of this invention, however, to provide an electrically operated actuator including a solenoid provided with a plunger, to operate the valve 31 and rotatably adjust the annular shutter 16. The electrically operated actuator may be mounted in a manner whereby the solenoid would be connected to the frame of the burner unit, and the plunger would be connected to the lever 38, the linking member 39 or the lug 54, so that upon energizing or de-energizing the solenoid, the plunger would be extended or retracted to move the linkage between the two desired positions. It is contemplated that such electrical solenoid would be controlled by thermo static switches disposed within the tobacco curing enclosure which would be capable of sensing the completion of the physiological transformation or yellowing stage of the tobacco leaves and actuate the solenoid to adjust the burner to the higher firing rate to produce a higher heat output for the dehydration stage.

Having thus described an embodiment of our invention, we claim:

1. A burner um't having at .least two different firing rates comprising blower means, conduit means communicating with said blower means for receiving air under pressure therefrom, fuel pump means, prime mover means for driving said blower means and said fuel pump means, first and second nozzles disposed in said conduit means, ignition means disposed adjacent said nozzle means, a first fuel supply line intercommunicating said fuel pump and said first nozzle means, a second fuel supply line intercommunicating said fuel pump and said second nozzle means, said second fuel supply line having valve means normally disposed in a closed position, said blower means having at least one air intake port and shutter means registerable with said air intake port and movable to at least first and second operating positions to vary the effective opening of said air intake port, actuating means operatively interconnecting said valve and said shutter means movable to a first position to close said valve and restrict the effective opening of said air intake port thereby permitting a supply of fuel through only said first supply line to said first nozzle means and a restrictive supply of air to said conduit means to provide a first firing rate, and movable to a second position to open said valve and increase the effective opening of said air intake port thereby permitting a supply of fuel through both fuel supply lines to said nozzle means and an increased supply of air to said conduit means to pro vide a second firing rate.

2. A burner unit according to claim 1, wherein said actuating means includes lever means operatively connected to said valve for opening and closing said valve and linking means operatively interconnecting said lever means and said shutter means.

3. A burner unit according to claim 1, including means disposed in said conduit means for imparting a swirling motion to said supply of air under pressure.

4. A burner unit according to claim 1, wherein said actuating means comprises an electrically operable solenoid.

5. A burner unit according to claim 1, wherein said ignition means comprises a pair of electrodes having electrical supply means.

6. A burner unit according to claim 1, wherein said blower means is provided with a plurality of circumferentially spaced air intake ports and said shutter means is slidably mounted on said blower means and is provided with a plurality of circumferentially spaced ports registerable with the air intake ports of said blower means when said shutter means is rotatably adjusted on said blower means by said actuating means to vary the effective openings of said air intake ports of said blower means.

7. A burner unit according to claim 6, wherein said actuating means includes lever means operatively connected to said valve for opening and closing said valve when said lever means is rotated about its pivotal connection with said valve, and rigid linking means pivotally connected to an arm portion of said lever means at one end thereof and connected to said shutter means at the opposite end thereof whereby when said lever means is pivoted said valve may be opened and closed and said shutter means is rotatably adjusted on said blower means to vary the effective opening of said air intake ports of said blower means.

8. A burner unit according to claim 7, wherein said lever means is movable to first and second positions.

'9. A burner assembly according to claim 7, wherein said valve includes a fluid passageway therethrough having a valve seat, a valve element engageable with said valve seat to obstruct said valve passageway, a valve stem secured to said valve element and extending to the exterior of said valve and biasing means for urging said element into engagement with said valve seat thereby obstructing said valve passageway, and said lever means having a bifurcated end portion receiving the outer end of said valve stem between the ear portions thereof, the portion of said valve stem received within the bifurcated end portion of said lever means being pivotally connected to the ear portions of said bifurcated end portion, said bifurcated end portion of said lever means having a continuous cam surface disposed parallel to the axis of pivotal connection between said valve stem and said bifurcated end portion, urged into engagement with a bearing surface of said valve including portions thereof disposed at different distances from said axis whereby said lever means can be pivoted about its pivotal connection with said valve stem to seat and unseat said valve element.

'10. A burner unit according to claim 1, wherein said second fuel supply line communicates directly with said first fuel supply, and including a valve disposed in said first supply line between said fuel pump and said second fuel supply line, normally disposed in the closed position and operable responsive to a predetermined pressure on the inlet side thereof for opening.

References Cited UNITED STATES PATENTS EDWARD G. FAVORS, Primary Examiner 

